It is known in the art relating to engines to use intake camshaft phasing (cam phasing) to vary intake valve closing (IVC) from normal to early or late closing in order to vary the quantity of intake air admitted to or retained in the cylinders. In engines with multiple cylinder banks, such as V-type engines, cam phasing may be obtained through separate cam phasers operable to control the timing of the intake camshafts provided for each cylinder bank.
Balancing of the output of the cylinders of the separate banks may be accomplished by electronic sensing of the angular position of mechanical targets provided on each cam phaser or camshaft. However, this does not ensure bank-to-bank balance of airflow, since manufacturing and assembly tolerances may result in some differences between sensed cam positions and actual valve timings.
These differences may be relatively unimportant when intake valve closing (IVC) occurs near the bottom dead center piston position, because changes in cylinder charge volume per crank angle change are low. However, the charge volume variations at valve closing increase during early or late valve closing, due to increased piston speeds farther from bottom dead center which result in greater variations in cylinder air charge and resulting cylinder power output. Thus, a more accurate method of balancing the output of multiple banks of engine cylinders is desired.